Control device and barrier bag therefor

ABSTRACT

This disclosure describes a control device such as a float actuated switch including a housing having first and second compartments therein with a float in the first compartment and a switch operated by the float in the second compartment. A flexible barrier bag at least partially surrounds the second compartment and contains a liquid for operating the float. A seal is formed integrally with the barrier bag and the bag is attached to the housing by clamping a peripheral segment of the bag against the housing. A vent passage vents the interior of the bag to a predetermined pressure.

United States Patent 2,639,005 5/1953 Gerstmann Samuel M. Jarvis Honolulu, Hawaii;

Jullus P. Strlegler, Fountain Valley, Calit. 797,542

Feb. 7, 1969 Aug. 31, 1971 AcmeDlvac Industries Inc.

Hawthorne, Calif.

lnventors Appl. No. Filed Patented Assignee CONTROL DEVICE AND BARRIER BAG THEREFOR 6 Claims, 4 Drawing US. Cl. 200/84 C, 200/83 Int. CL .L.H0lh 35/18 Field of Search 200/83,

References Cited UNITED STATES PATENTS 'Prr'mary Examiner-David Smith, Jr.

An0rney-Smyth, Roston and Pavitt ABSTRACT: This disclosure describes a control device such as a float actuated switch including a housing having first and second compartments therein with a float in the first compartrnent and a switch operated by the float in the second compartment. A flexible barrier bag at least partially surrounds the second compartment and contains a liquid for operating the float. A seal is formed integrally with the barrier bag and the bag is attached to the housing by clamping a peripheral segment of the bag against the housing. A vent passage vents the interior of the bag to a predetermined pressure.

CONTROL DEVICE AND BARRIER BAG THEREFOR BACKGROUND OF THE INVENTION Input is often provided to a control device such as a switch by a float. Various liquid level sensing devices utilize floats which contact the liquid and which are buoyed thereby to a level which provides an indication of the level of the liquid in the container. For example, the switch may be responsive to the float being at a predetermined low level to start a pump and supply additional fluid container. I

When the fluid being controlled is of a type which would corrode or destroy the float, it is necessary toshield the float from the corrosive fluid. This can be accomplished by enclosing the float in a chamber which is partially defined by a flexible member. The chamber contains a fluid, preferably a liquid,

which will not corrode the float and which buoys the float upw wardly as the liquid from the outside of the chamber acts on the flexible member to cause elevation of the liquid within the bag.

SUMMARY OF INVENTION The present invention provides a simple and inexpensive way to attach the flexible member to the control device. According to the present invention, the flexible member is preferably in the form of a flexible barrier bag which at least substantially surrounds the float, and the control device has two separable sections between which a peripheral segment of the barrier bag can be clamped to firmly retain the barrier bag. As the barrier bag is attached to the control device by two sections thereof, there is no need to employ separate fasteners or clamping members to attach the barrier bag. As the two sections of the control device are movable, the barrier bag can be easily removed and replaced when desired.

As the barrier bag is to contain a. liquid, it is important that a tight seal be provided between the barrier bag and the control device. According to the present invention, this is accomplished by a seal ring formed integrally with the barrier bag. Thus, when the barrier bag is attached to a control device, the seal is automatically present to tightly seal the joint between the barrier and the control device.

Another feature of the present invention is that the barrier bag is readily adapted for attachment to existing control devices. Although the barrier bag can be used with many different control devices, it is particularly adapted for use with a float operated switch of the type including a switch housing, a switch within the housing, a float, means for mounting the float for movement along a predetermined path, a cage for housing the float and attachable to the switch housing with surfaces of the cage and the housing, respectively, being adjacent. The switch is actuable in response to predetermined movement of the float along the path. The barrier bag has an opening therein sized to receive the cage. Preferably, the barrier bag is sufficiently large to completely enclose the cage.

A peripheral segment of the barrier bag can be releasably clamped by the adjacent surfaces of the cage and switch housing to thereby attach the barrier bag to the device. The seal is formed integrally with the barrier bag and is adjacent the peripheral segment of the bag. In a preferred form of the invention, an annular groove is defined by one or both of the cage and the switch housing for receiving the seal.

The position of the float within the barrier bag is dependent upon a number of factors including the height of the liquid outside of the barrier bag and the quantity and specific gravity of the liquid within the bag. Of course, the position of the float controls the actuation of the control device. The present invention provides for changing of this actuation point by varying the quantity and specific gravity of the liquid within the barrier bug. Because the barrier bag is readily detachable, this change of liquid or liquid quantity can be easily accomplished.

Another factor effecting the elevation of the float is the pressure within the barrier bag. For example, when the barrier bag is employed in a pressurized tank, and the pressure of the fluid therein is at atmospheric, the result is that the pressure within the tank may elevate or prevent the elevation of the float independently of the liquid level of the tank. This causes the control device to operate improperly and inaccurately. The present invention teaches that this problem can be overcome by venting of the interior of the barrier bag to a pressure equal to the pressure acting on the fluid in the tank. This cancels out the effect of the pressure acting on the liquid in the tank and allows the air in the barrier bag to escape from and return to the barrier bag as necessary. That is, this venting arrangement allows the float of elevation to be controlled solely by the buoyancy effect and this is most desirable.

The invention, both as to its organization and method of operation together with further features and advantages thereof may best be understood be reference to the following description taken in connection with the accompanying illustrative drawings. I

BRIEF DESCRIPTION OF THE DRAWINGS DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring to the drawings and in particular to FIG. 1 thereof, reference numeral 11 designates a control device in the form of a float actuated switch having a barrier bag 13 attached thereto. Although the barrier bag 13 can be used in many different environments, it is particularly adapted for use with the float actuated switch 1 1.

The float actuated switch 11 includes a switch housing 15 and a cage 17 defining compartments 19 and 21. A rod 23 is suitably rigidly attached to a central portion of the lower wall 25 of the switch housing 15 as by welding. The cage 17 is preferably cylindrical and is mounted on the switch housing 15 by a nut 27 which receives a lower threaded end portion of the rod 23 and cooperates therewith to mount the cage 17 on the switch housing 15.

The switch 29, which has a depressible actuating element 31 is suitably rigidly mounted within the switch housing 15 as by a bracket 33. The switch 29 is electrically connectable to an external circuit by conductors 35 which project through a closure member 37 which forms an upper'wall for the switch housing 15.

Although the switch 29 can be actuated in any suitable manner, in the embodiment illustrated, the actuation is accomplished magnetically; To this end, a permanent magnet 39 is mounted on one end of an arm 41. The arm 41 is suitably pivotally mounted within the switch housing 15 by a pin 43. The arm 41 has an actuator section 45 which can engage and depress the actuating element 31 of the switch 29 when the arm 41 pivots in the clockwise direction about the pin 43. Depression of the actuating element 31 can result in opening or closing of the switch 29, as desired.

A second permanent magnet means 47 which includes two separate magnets is mounted on the lower wall 25 of the switch housing 15 by a screw 49. If the screw 49 is loosened, the magnet means 47 can be rotated for an adjusting purpose described more fully hereinbelow. Of course, the magnet means 47 can be constituted by one or more individual permanent magnets.

A lightweight float- 51 is mounted on the rod 23 within the cage 17. The float 51 can be of any conventional float materifloat 51 has a bore 55 for loosely receiving the nut 27. An annular bearing 57 which may be constructed of Teflon or other suitable bearing material is mounted in a counterbore of the float 51 for movement with the float. The cage 17 has a plurality of apertures 59 to permit a noncorrosive liquid 61 such as water or antifreeze contained within the barrier bag 13 to enter the cage and control the elevation of the float 51.

The poles of the magnets 39 and 53 are arrangedso as to repel each other as the float 51 moves upwardly along the rod 23. Ultimately, however, elevation of the float 51 causes the magnet 53 to repel the magnet 39 with sufficient force to cause clockwise rotation of the arm 41 about the pin 43 a sufficient amount to depress the actuating element 33 to actuate the switch 39.

The magnet means 47 performs an adjusting function. The

I poles of the magnet means 47 are divided by the diameter of the magnet so that the poles are on the leftand righthand sides of the magnet as shown in FIG. 1. By loosening the screw 49 and rotating the magnet means 47, the magnet means 47 can be caused to attract or repel the magnet 53 to thereby permit adjustment of the actuation point of the switch 29. Operation of a float switch of this type is more fully described in US. Pat. No. 3,293,579.

Turning now to the features of the barrier bag 13, the bag may be constructed of any relatively flexible material which will not be corroded in the substance in which it is to be immersed. In the embodiment illustrated, the bag 13 is generally cylindrical and has a diameter greater than the diameter of the cage 17 and an axial dimension longer than that of the cage 17. The bag is fluidtight so that it completely shields the float 51 from any contaminating liquid in which the bag may be immersed. The upper end of the bag is open as shown in FIG. 1 so that the cage 17 may be inserted therein.

According to a preferred method of attaching the bag 13, the switch housing has a downwardly facing surface or shoulder 63 which forms the upper surface of an annular groove 65 in the switch housing. The cage 17 terminates upwardly in a rounded annular upper surface 67.

The barrier bag 13 has a peripheral segment 69 (FIGS. 2 and 2A) which is of reduced thickness. In the embodiment illustrated, the thickness of the peripheral segment 69 is reduced by an annular groove 71 formed on the interior surface of the bag 13. The bag terminates in an integral, annular, resilient seal or sealing bead 73 which extends completely around the upper end of the bag. The seal 73 is of increased thickness relative to the peripheral segment 69 and to the wall thickness of the bag adjacent the peripheral segment 69.

As shown in FIG. 2, the bag 13 is releasably connected to the control device 11 by clampingly gripping the peripheral segment 69 of the bag between the shoulder 63 and the surface 67. With this arrangement, the surface 67 is received within the groove 71 so that the bag 13 is retained by the clamping action of the shoulder 63 andthe surface 67 as well as the mechanical interlocking action between the upper end of the cage 17 and the groove 71. Thus, the bag 13 is attached without the need for any separate fastening means.

If desired, the upper end of the cage 17 may be provided with an annular shoulder 75 which limits movement of the cage 17 toward the shoulder 63. By limiting the movement of the cage 17 toward the shoulder 63, severance of the peripheral segment 69 by the surfaces 63 and 67 is positively prevented.

The bag 13 is preferably constructed of a resilient material so that the upper end thereof is readily adapted to form a seal. In the illustrated embodiment, the seal 73 is received within the groove 65 to form a tight seal between the bag 13, the switch housing 15 and the cage 17. As the cage 17 is moved axially toward the shoulder 63, the resilient material of the peripheral segment 69 is subjected to a compressive force thereby tending to move the material laterally in both directions from the surface 67. This flow of the resilient material tends to substantially fill the groove 65 with the resilient material to thereby improve the sealing action obtainable.

The upper end portion of the bag 13 is provided with an integral fitting 77 having a vent passage 79' extending upper end of the vent tube 81 is provided with a threaded fitting 87 to which can be attached a vent pipe 89.

The float actuated switch 11 can be immersed in a corrosive fluid 91 within a tank 93 (FIG. 3). The float actuated switch 11 is suitably mounted at a predetermined level within the tank 93 to assure actuation of the switch 29 when the level of the liquid 91 reaches a predetermined elevation. As illustrated in FIG. 3, the float actuated switch 11 may constitute a portion of a low level alarm or a low level control. The vent pipe 89 provides communication between the interior of the barrier bag 13 and a location in the tank 93 above the level of the liquid 91. In this manner, it can be assured that the pressure within the bag 13 will be substantially equal to the pressure within the tank. The movement of the float 51 is then controlled substantially completely by the buoyancy effect except for the magnets 39, 47 and 53. Thus, the liquid 91 acts through the flexible bag 13 to cause the liquid 61 to raise or lower the float 51 as the liquid level of the liquid 91 is raised or lowered.

The specific gravity of the liquid 61 must be less than the specific gravity of the liquid 91 so that the liquid 61 can be readily moved by the liquid 91.

Although exemplary embodiments of the invention have been shown and described, many changes, modifications and substitutions may be made by one having ordinary skill in the art without necessarily. departing from the spirit and scope of this invention.

We claim: 1. In a float switch adapted for placement in a first fluid and including a switch housing, a switch within the housing, a float, means for mounting the float'for movement along a predetermined path, cage means for housing the float and attachable to the switch housing with surfaces of the cage means and the housing, respectively, being adjacent each other and meansresponsive to predetermined movement of the float along the path to actuate the switch, the improvement comprising;

an at least substantially flexible barrier bag of a size to fit over said cage means, said barrier bag having an opening of sufficient area to receive the cage means, said barrier bag being impervious to said first fluid and forming a fluid impervious barrier between the first fluid and the float;

said barrier bag having a peripheral segment adjacent said opening, said peripheral segment being clamped between said surfaces of the cage means and the switch housing to thereby attach the bag to the float switch; and

said barrier bag having a resilient seal integral therewith and adjacent the peripheral segment tightly sealing the barrier bag to the cage means and the housing, the barrier bag being adapted to receive a second fluid so that the float is made responsive to variations in the level of the first fluid by the second fluid.

2. An improvement as defined in claim 1 wherein said seal is I thicker than said peripheral segment.

3. An improvement as defined in claim 1 wherein said barrier bag has a vent aperture therein for venting the region of said barrier bag above the level of the second fluid therein.

4. A float controlled device (for immersion within) respon-' control means on the supporting structure responsive to a predetermined movement of the float along said path for providing a signal;

a flexible barrier bag having an opening for at least partially receiving the float;

means for mounting the barrier bag on the supporting structure with said barrier bag at least partially enclosing the float(,) and substantially completely isolating said float from the first liquid, said barrier bag being adapted to contain a second liquid to move the float along said path in response to variations in the level of the second liquid, said barrier bag being engageable with the first liquid whereby variations in the level of the first liquid cause movement of the float along said path;

I means for preventing the barrier bag from hampering movement of the float along said path; and

vent means for providing communication between the interior of said barrier bag above the levelof the second liquid and a location which is at approximately said predetermined absolute pressure whereby said float is subjected to said predetermined pressure and movement of said float is caused by the effects of buoyancy.

5. A device as defined in claim 4 wherein the container is closed and said predetermined pressure is greater than standard atmospheric pressure, said vent means extending to a location within the container above the level of the first fluid whereby the float is subjected to the same pressure that exists within the container. v

6. An improvement as defined in claim 1 wherein said seal is received between said surfaces of the cage-means and the switch housing. 

1. In a float switch adapted for placement in a first fluid and including a switch housing, a switch within the housing, a float, means for mounting the float for movement along a predetermined path, cage means for housing the float and attachable to the switch housing with surfaces of the cage Means and the housing, respectively, being adjacent each other and means responsive to predetermined movement of the float along the path to actuate the switch, the improvement comprising; an at least substantially flexible barrier bag of a size to fit over said cage means, said barrier bag having an opening of sufficient area to receive the cage means, said barrier bag being impervious to said first fluid and forming a fluid impervious barrier between the first fluid and the float; said barrier bag having a peripheral segment adjacent said opening, said peripheral segment being clamped between said surfaces of the cage means and the switch housing to thereby attach the bag to the float switch; and said barrier bag having a resilient seal integral therewith and adjacent the peripheral segment tightly sealing the barrier bag to the cage means and the housing, the barrier bag being adapted to receive a second fluid so that the float is made responsive to variations in the level of the first fluid by the second fluid.
 2. An improvement as defined in claim 1 wherein said seal is thicker than said peripheral segment.
 3. An improvement as defined in claim 1 wherein said barrier bag has a vent aperture therein for venting the region of said barrier bag above the level of the second fluid therein.
 4. A float controlled device (for immersion within) responsive to the level of a first liquid within a container wherein the first liquid is (subjected to) at a predetermined absolute pressure, (the combination of) said device comprising: a supporting structure; a float; means for mounting the float on said supporting structure for movement along a predetermined path; control means on the supporting structure responsive to a predetermined movement of the float along said path for providing a signal; a flexible barrier bag having an opening for at least partially receiving the float; means for mounting the barrier bag on the supporting structure with said barrier bag at least partially enclosing the float(,) and substantially completely isolating said float from the first liquid, said barrier bag being adapted to contain a second liquid to move the float along said path in response to variations in the level of the second liquid, said barrier bag being engageable with the first liquid whereby variations in the level of the first liquid cause movement of the float along said path; means for preventing the barrier bag from hampering movement of the float along said path; and vent means for providing communication between the interior of said barrier bag above the level of the second liquid and a location which is at approximately said predetermined absolute pressure whereby said float is subjected to said predetermined pressure and movement of said float is caused by the effects of buoyancy.
 5. A device as defined in claim 4 wherein the container is closed and said predetermined pressure is greater than standard atmospheric pressure, said vent means extending to a location within the container above the level of the first fluid whereby the float is subjected to the same pressure that exists within the container.
 6. An improvement as defined in claim 1 wherein said seal is received between said surfaces of the cage means and the switch housing. 